This invention relates generally to the detection of hemolysis and subsequent development of neonatal jaundice, and more particularly the invention relates to improved apparatus for hospital nursery use in sampling and analyzing end tidal breath for carbon monoxide content as an indication of jaundice. The invention has further applications in the detection of other exhaled gasses.
Infant hemolysis leading to hyperbilirubinemia and jaundice is a significant clinical problem which results directly from increased bilirubin levels in the infant body. As discussed in U.S. Pat. No. 4,831,024 issued to Vreman and Stevenson for "Method to Prevent Neonatal Jaundice" the toxic cause of jaundice and treatment thereof are known. However, in the newborn, or neonate, the visible signs of the disorder usually manifest themselves several days after birth, often after the infant and mother have been discharged from the hospital.
A simple non-invasive test for hemolysis and subsequent jaundice is based on carbon monoxide analysis of end expiratory breath sample collected transnasally. As described by D. W. Smith, et al., Journal of Pediatric Gastroenterology and Nutrition (1985) 4: 38-44, samples of end-expiratory breath are collected by transnasal placement of a catheter into the posterior nasal pharynx. Expired gas is drawn manually by nursery personnel in small, less than 1 ml, increments at end expiration as determined by the infants chest wall movement. A syringe of sufficient size such as 12 cc is used to permit the collection of a total of approximately 10 ml of expired breath. Ambient air is also sampled, and the sampled measurements are corrected for the contribution of ambient CO which can vary in the range of 0.2-10 .mu.l/l. The CO in the samples is then measured in a laboratory using gas chromatography.
C. Y. Yeung, et al. describe in the Lancet Volume 337: Jan. 12, 1991 pp. 90-93 apparatus for collecting end expiratory air samples. A hot wire sensor consisting of a set of seven tungsten hot wires is cooled by expired air flow which causes an imbalance in a Wheatstone bridge circuit. The bridge circuit sends a signal to a syringe driver controller which then collects an end expiratory air sample. A variable time switch can be set to delay the collection of samples. The air sample is then analyzed in a laboratory for hydrogen content to detect lactose malabsorption.
The present invention provides apparatus for use in a nursery, clinic, or physician's office for automatic sampling and analyzing end expiratory air without the requirement for laboratory analysis or highly trained personnel.